Autonomous or semi-autonomous machines, such as dozers, are used to perform a number of earthmoving operations at a worksite. In such machines, minimal operator supervision may be required for operating the machine. Sometimes, the operator may be seated at a remote location and may operate a fleet of the machines from the remote location at the same time.
Dozers may be used to perform earthmoving operations that involve three distinct phases known as dig, carry, and dump. Operations may involve either push-to-edge or backstacking a number of piles of material on a surface of the worksite. Generally, a stale terrain value limit may be set for the dump operations near an edge such that on approaching the stale terrain value limit, the operator may need to intervene to check that the dozer is performing tasks as required. Such intermittent checking of the terrain on which the dozer operates may be required when more than one of the dozers operates at the worksite, since movement of other dozers may affect certain aspects of the terrain.
In backstacking operations, in which sometimes multiple layers may be thrilled on the work surface, each layer including a number of piles of the material, it may be essential to gain confidence on the terrain on which the dozer operates. A stale terrain is indicative that the dozer has not visited and/or updated the terrain for a predefined period of time, resulting in lower confidence in the terrain. Presence of stale terrain on the worksite is assumed to exist on approaching the stale terrain value limit.
However, setting an optimal stale terrain value limit may be challenging, if the stale terrain value limit is set low, the operator may need to frequently check the operation of the dozer, increasing stress and pressure on the operator, sometimes leading to delays in operation and affecting an overall productivity of the system. On the other hand, if the stale terrain value limit is set high, the operator may rarely check the system. In some situations, untoward changes in the terrain may take place due to presence of other dozers at the worksite or other reasons, leading to undesired terrain characteristics. Hence, there is a need to determine an optimum timing strategy for operator intervention in controlling the autonomous operation of the machine.
U.S. Pat. No. 9,163,384 describes a system for automated control of a machine. The system has a ground engaging work implement including an implement load sensor system. A controller determines a change in terrain based at least in part upon a change in the load on the ground engaging work implement. If the change in terrain exceeds a stale terrain value, the controller generates an alert command signal.